The present invention relates to an arrangement for measuring localized impact forces and pressures applied to the test dummy head. In automotive crash testing, test dummies are used in order to help evaluate the effects of the impact forces. Heretofore, only the accelerations of the head have been available for estimation of facial loads. The most common method of estimating these head loads is that described in Federal Motor Vehicle Safety Standards (FMVSS) 208, utilizing arrays of accelerometers mounted in the dummy head. Traditionally, this method has been used to provide estimates of linear accelerations which are used to estimate the severity of the acceleration loads to the brain.
Head acceleration measured according to the FMVSS 208 procedure is not sufficient to detect localized impacts that cause many of the important facial injuries, which are often related to penetrating fractures of the facial bony structures by poorly-distributed loadings. It is known that there exists a wide range of load limits for different zones of the face. Further, the head acceleration method does not take into account the fact that contact areas are time-variable. A further shortcoming of the existing accelerometer methods, is that they are not able to readily detect localized hard points in the contacted surface.
Previous attempts to measure localized facial loads have met with only partial success. These attempts include sintered foam systems with different foam formulations for different pressure ranges, and various systems using pressure-sensitive films to differentiate pressure levels which generate color or pigment gradients (see (1) "Biofidelity Improvements to the Hybrid III Headform," Newman, J. A. and Gallup, B. M., Proceedings of the 28th Stapp Car Crash Conference, November, 1983; and (2) "Injury Criteria for Combined Restraint Systems", Grosch, Lothar, 10th ITCESV, Oxford, England, July 1-5, 1985). These methods also involve certain shortcomings, however, such as one-time usage; a narrow range of pressures over which each may be used; results which are difficult to interpret; and a complete lack of load-time history data necessary for modeling and extrapolation.
It is, therefore, an object of the present invention to minimize or obviate problems and shortcomings of the types discussed above.
A further objective is to enable the measurement of localized facial impact forces and pressures sustained by the head of a crash test dummy.
An additional objective is to provide an arrangement for measuring the impact forces and pressures applied to the head of a crash test dummy which senses the instantaneous amplitude as well as the duration of these pressures and forces, i.e., time-histories.